Cool idea! Demo didn't work for me on latest version of Chrome and a brand new MacBook Air though, and gave it a pretty good shot. I'm sure you didn't put this up without testing that it works, just didn't work after about 3-5 minutes of trying everything for me.
Didn't work for me either (on chrome). I kinda felt like a moron waving my hands around trying to get it to work. Would have been cool if the camera was doing a live capture and would let me watch my moronic movements after a while.
This was exactly what I was thinking when it didn't work for me; the book page would finally turn and show all kinds of people doing swipes (in all possible ways) in the air... (Macbook Air 2011, latest Chrome).
For a demo like this where failures can be caused by user error instead of app error, you should consider overlaying a tiny rectangle on screen that shows the webcam captured frames with an overlay of the recognition, so it's easier to tell if it's user error.
